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Diversity of Mechanisms for Boron Toxicity in Mammals
Published in Debasis Bagchi, Manashi Bagchi, Metal Toxicology Handbook, 2020
Diana Rodríguez-Vera, Antonio Abad-García, Mónica Barrón-González, Julia J. Segura-Uribe, Eunice D. Farfán-García, Marvin A. Soriano-Ursúa
Accordingly, boric acid and borates have been widely administered to mice (Table 26.1). A detailed description of BCCs toxicity and kinetics in mice is beyond the aim of this chapter. However, the high variability of these features is observed depending on the analyzed BCCs. For example, the determination of boron concentrations in blood showed that in the first group of mice administered intravenously with 0.5 mg of sodium pentaborate, boron blood levels were 40 ppm after 1 min, which decreased to 18 ppm after 2 h; in the second group administered with 2.1 mg of sodium pentaborate, the boron blood levels were 158 ppm after 1 min, which decreased to 40 ppm after 2 h. These results suggest a two-order clearance with a rapid phase in the beginning. In both groups, boron was mainly eliminated in the urine, and half of the administered boron was excreted within an hour for both doses (Konikowski and Farr 1965). The kinetics and toxicity of tavaborole and other BCCs have been described as well. Toxicity for neoplasia is minimal, even after a 2-year exposition (Ciaravino, Plattner, and Chanda 2013). Moreover, higher molecular weight compounds have been administered to mice, such as carboranes and boron-containing complexes, in doses up to 78 mg/kg body weight, which were well-tolerated and no morbidity or mortality was observed (Vicente et al. 2003).
Applications of Neutron Optics to Biomedicine: BNCT
Published in Maria L. Calvo, Ramón Fernandez Álvarez-Estrada, Advances in Neutron Optics, 2019
The Brookhaven Graphite Research Reactor (BGRR) of the Brookhaven National Laboratory (BNL) was the neutron source used for the first clinical trials performed by Sweet and coworkers. This was the first peace-time reactor built in the United States following World War II, and its primary mission was to produce neutrons for scientific experimentation and to refine reactor technology. In 1959, a second reactor Brookhaven Medical Research Reactor (BMRR) built specifically for medical applications, including BNCT, and equipped with a treatment room started operations and was used for clinical trials. Also, the Massachusetts Institute of Technology Reactor (MITR) was used during these years. Different boron compounds were tested, such as boric acid, sodium pentaborate, and derivatives of phenylboronic acid. A detailed description of these clinical trials can be found in Ref. [4]. The results were not successful, and this was addressed to the low selectivity of the boron compounds and to the poor quality of the neutron beam (excessive presence of gamma rays in the beam). BNCT clinical trials were stopped in the 1960s in the United States, but these efforts opened the way to the continuation of the BNCT progress, which expanded to Japan.
Flame Retardance of Fabrics
Published in Menachem Lewin, Stephen B. Sello, Handbook of Fiber Science and Technology: Chemical Processing of Fibers and Fabrics, 2018
The solubility of the borate salts changes with the ratio Na2O: B2O3 and temperature, and highly soluble mixtures can be produced due to polyions being formed [7, 194]. Borax dissolves upon heating in its own water of hydration, produces a frothy mass, and finally changes to a clear melt. A mixture of 7:3 borax :boric acid (sodium pentaborate) is an effective flame retardant for cellulose at an add-on of 5%, but 20% is needed to decrease the glow resistance substantially. This mixture does not crystallize and upon heating produces a clear glassy layer that adheres uniformly to cellulose fibers. The water vapor from the hydration of the borax-boric acid mixture swells the surface of the fibers between 80–200°C and then a uniform intumescent coating on that surface solidifies as decomposition of the polymer continues. The solidified foam should be stable at 500°C [7], Sodium pentaborate, as well as sodium tetrafluoroborate, enhances char formation. In the first case, the dehydration of the cellulose probably occurs via the formation of borate esters which act similarly to phosphate esters. In the case of sodium tetrafluoro-borate, sodium fluoride and gaseous BF3 are formed upon decomposition. BF3 is known to catalyze the formation of ketone groups and double C=C bonds, which can cross-link and polymerize to form char [193].
Effect of addition of corrosion inhibitors on corrosion behaviors of PCV material under diluted artificial seawater environment
Published in Journal of Nuclear Science and Technology, 2019
Tetsuji Kaneko, Norihiko Tanaka, Shinichi Ishioka, Fujii Kazumi, Yuichi Fukaya, Katsuhiko Kumagai
The immersion corrosion test matrix is shown in Table 2. Here, the concentration of ZSCMP is expressed as the total phosphate ion concentration contained therein. The dilution ratio of artificial seawater was set to 1000-fold and 10,000-fold in which the chloride ion concentration was 19 and 1.9 mg‧L−1, respectively. The dilution ratio of artificial seawater was set based on the analysis result of chloride ion concentration in the PCV stagnant water [3,6]. The effect combined addition with each inhibitors and borate was tested. Sodium pentaborate was used as the borate, and the added concentration was 40, 400, and 12,000 mg·L−1 as boron. Here, 12,000 mg‧L−1 as boron is the maximum amount of boron necessary to prevent recriticality of fuel debris, and 400 and 40 mg‧L−1 as B is condition assuming the case that the boron concentration decreases in the PCV. Fukaya et al. reported that sodium pentaborate serves as the oxide film formation type corrosion inhibitor, and carbon steel shows uniform corrosion at 40 mg‧L−1, localized corrosion at 400 mg‧L−1, and passivation at 12,000 mg‧L−1 [3,7].
Antibacterial agents applied as antivirals in textile-based PPE: a narrative review
Published in The Journal of The Textile Institute, 2022
Zulfiqar Ali Raza, Muhammad Taqi, Muhammad Rizwan Tariq
There are many ways through which we could extend the antiviral activity is already in practice antimicrobial agents including functional group alteration, impregnation of new functionalities via chemical and nanotechnology approaches to achieve a broad-spectrum activity (Thi Ngoc Dung et al., 2020). Nanotechnology has also been used in developing the targeted drug carriers (Zhou et al., 2020; Falanga et al., 2011; Hallaj-Nezhadia et al., 2010), biomolecular sensing, rapid pathogen detection, and nanoparticles (NPs) labeled anti-cancer therapies (Thi Ngoc Dung et al., 2020; Kennedy et al., 2011). The NPs used as antiviral agents target the viruses during their interaction and possible entrance through the treated PPE. Metal-based NPs of silver, gold, titanium, and copper exhibit broad-spectrum antiviral activity. The interaction of such NPs with the virus surface isn’t done in a random fashion but in a scientific way. For instance, the silver’s mode of action as antimicrobial agent corresponds to the formation of silver ions (Ag+). The formation of such ions strongly inhibits the microbial growth by suppressing the respiratory enzymes’ activity and electron transportation and interfering the functions of DNA. Due to such properties, Ag+ ions and silver compounds have extensively been used against antiviral, antibacterial and antifungal infections i.e. complete range of microbes. The benefit to impregnate the silver NPs is to control release the Ag+ ions for a sustainable antimicrobial efficacy. The silver NPs had also been found effective against HIV, hepatitis B, herpes simplex HSV, respiratory syncytial RSV, and the poxviruses. For instance, the silver NPs in the size range of 1-10 nm had shown antiviral activity against HIV (Thi Ngoc Dung et al., 2020). A study conducted in Japan expressed the immobilization of silver NPs onto textile fabrics via a radiochemical procedure; the resultant fabric exhibited good antiviral activity (Liu et al., 2019). A group of researchers developed surgical gowns coated with TiO2 which qualified the viral penetration test of the ASTM 1671, mandatory for healthcare PPE (Parthasarathi and Thilagavathi, 2013). Likewise, triclosan with sodium pentaborate pentahydrate had been implicated onto cotton fabrics. The treated fabrics exhibited good antiviral activity against adenovirus and the polioviruses (Catel-Ferreira et al., 2015).